1. Field of the Invention
The present invention relates to an audio signal processing device, and more specifically, to an audio signal processing device that emphasizes a predetermined audio signal.
2. Description of Related Art
In recent years, techniques for performing various processes on audio signals have been proposed for the purpose of improving the quality of sound transmission or sound recognition rate. Japanese Unexamined Patent Application Publication No. 2006-197552 and Alexander Jourjine, Scott Rickard, Ozgur Yilmaz, “BLIND SEPARATION OF DISJOINT ORTHOGONAL SIGNALS”, ICASSP2000 (Alexander et. Al.) propose one technique for emphasizing an audio signal (hereinafter referred to as a desired audio signal) that complies with a predetermined condition and suppressing undesired signals other than the predetermined audio signal using a sound source separation technique.
Japanese Unexamined Patent Application Publication No. 2006-197552 discloses a technique of performing sound source separation of a target sound and a disturbance sound by a linear combination process of audio signals input to a plurality of microphones to emphasize the target sound. Alexander et. Al. discloses a method for generating a time-frequency mask in a frequency area, emphasizing a desired signal and suppressing other undesired signals by a masking process, thereby separating audio signals into signals for each sound source. Specifically, Alexander et. Al. calculates an amplitude ratio and a phase difference for each of time-frequency components from audio signals input from two sensors to generate a two-dimensional histogram, and clusters the time-frequency component in the histogram to calculate peak coordinates (amplitude ratio, phase difference) for each sound source. A time-frequency mask is then generated based on the coordinates to carry out processing for multiplying an original signal by a mask. According to this method, the sound source separation effects are obtained.